Archive for the ‘Twinassist’ tag

As diesel engines proliferated and as engine builders found ways to make their products more powerful during the Fifties and Sixties, the need for dual-engine setups in cabovers – such as the ones that hauled B-24 bomber parts during World War II – should have disappeared. Lloyd J. Wolf, however, thought otherwise, and made adding power to over-the-road trucks via additional engines a decades-long obsession.

As prolific an engineer and inventor as he was, we don’t know much about Wolf. He got his professional start in the late 1940s by designing couplings, clutches, and transmissions for the Twin Disc Clutch Company in Racine, Wisconsin – work that he would draw from in his later inventions – but, from what we see in that later work, he also apparently had plenty of familiarity with trucks and the trucking industry that he likely didn’t pick up while with Twin Disc.

Sometime in the early 1950s, he moved from Racine to Irving, Texas, where he appears to have established a freelance engineering firm and began to consider two separate issues of concern to the heavy-hauling truck industry: getting the load on the trailer, and generating enough oomph to move it.

He set about solving the latter problem first by pairing the truck’s conventional engine with a booster engine. While earlier efforts to add a second engine also added a second complete drivetrain to the tractor, Wolf designed a system that had one engine operating normally through a manual transmission and a second engine operating through an automatic transmission that coordinated with the manual transmission to match its speed. Both transmissions then sent their output into a geared or chained coupling – much like multi-engine pulling tractors – that then directed the combined output through a single driveshaft to the tractor’s rear axle.

Wolf filed his first patent (3027962, updated in 3090458) for what he would later brand the Twinassist in June 1956 while still living in Irving, but he would pursue it over the next several years. A move to Dallas in the late 1950s – probably right around the time he incorporated Lloyd J. Wolf and Son in November 1958 – likely coincided with the start of Twinassist manufacture, using Emeryville-series International cabovers and paired GMC six-cylinder engines, as seen in the lead photo, which we culled from Fred Crismon’s U.S. Military Wheeled Vehicles. The engines rolled forward on a cart for servicing, and Crismon wrote that Wolf had developed a quick-disconnect system that “allowed the entire power unit to be removed in seven minutes.”

Not long after incorporating the business, Wolf managed to get a writeup in Popular Science, which quoted Wolf as saying that the two GMC sixes weighed and cost less than an engine of equal horsepower. “At cruising speed, one engine idles – saving fuel – while the other pulls the load. As acceleration increases, the idling engine revs up to help its mate.” The Popular Science article also highlighted a couple other Wolf innovations designed to cheaply add power to trucks hauling heavy loads, including a piggyback trailer with its own drivetrain and fifth wheel that sandwiched between the tractor and the trailer, and the Dynassist, which was the piggyback trailer idea extended to a full-size trailer. Wolf pitched the Dynassist as an easy-to-install add-on system for trucking company operators to cut their costs and at the same time boost payloads and provide power enough to level out hilly roads and highways.

Wolf appears to have recognized a good naming convention when he saw one, so when he set about to solve the problem of how to get heavy loads onto flatbed trailers, he called it the Loadassist. The whole concept of the Loadassist revolved around the trailer’s tandem axle assembly, which Wolf attached to a bogie of sorts that slid forward and backward underneath the trailer. Sliding the bogie forward allowed the trailer to articulate so that its tail end rested on the ground, making it easier to pull (or drive) the load up from the ground onto the trailer. After loading, the bogies then slid back to their regular position, the flatbed flattened out again, and the driver could go on his merry way.

As we see from the above photo from Crismon, which features a Twinassist tractor with a Loadassist trailer, the setup worked well enough to transport light tracked vehicles, so Wolf and the St. Louis Car Company approached the U.S. Army with the idea in the early 1960s. Crismon noted that the Army tested the concept in April 1961 at Fort Eustis, Virginia, but doesn’t say whether the Army and bought any Twinassists or Loadassists. Regardless, Wolf filed for a patent on the idea in August 1962.

Wolf’s association with the St. Louis Car Company (and its parent company, General Steel) came about when he designed the Wolfwagon, an integrated tractor and trailer that could be hitched to as many as five other Wolfwagons in a train and controlled from the lead car. According to Jeff Lakaszcyck of the American Truck Historical Society, St. Louis Car Company built Wolfwagons from 1956 to 1964 in both two- and three-axle variants and in both integrated cab and half-cab styles. According to truck enthusiast Fred Veregge, “The idea was that you would load in one city for delivery in the next city without having to cross-dock the freight. The driver had an inside door leading to the freight compartment. The engine set in the middle and you could only check the radiator thru an inspection door in the freight box. These wagons were hard to control, as back then they didn’t know to put the lighter one on the back. I always remember this one old timer returning from Kansas City down old highway 13 describing his experience. ‘The only time I was on the road was when I crossed it.'”

Studying the photo above, it appears that Wolf simply built a ribbed aluminum box body atop his Dynassist trailer system, added a steerable front axle, and worked out a way to control other trucks remotely. He patented the idea in April 1963 (3255837, updated in 3326314), but a pair of steerable trailer patents (3430975 and 3447813, both filed in 1967) and a separate patent for a control cable coupling also seem to have come out of the design.

While we don’t know how long Lloyd J. Wolf and Son remained in business or what happened to Wolf afterward, we can see from his patent work that he continued to design truck and trailer components – focusing largely on tandem axle suspensions and braking systems – from the Dallas location through the early 1970s. He then apparently retired to Roanoke, Texas, from where he filed one last patent – for a bubble level for a power drill – in June 1973.